This invention relates to tufting machines and more particularly to apparatus for connecting a needle bar of a tufting machine to a pattern control which permits the needle bar to move laterally as driven by the pattern control while permitting the needle bar to reciprocate in a path normal to the lateral movement.
In the art of tufting one or more rows of yarn carrying needles are reciprocably driven through a base material fed through the tufting machine to form loops that are seized by loopers or hooks oscillating below the base material in timed relationship with the needles.
The needles are typically carried by a needle bar supported at the end of a plurality of push rods constrained for reciprocatory motion toward and away from the loopers or hooks. In those machines having a sliding needle bar arrangement, i.e., wherein the needle bar is controllably driven by pattern means transverse to the direction of movement of the backing material so as to break up the alignment of longitudinal rows of tufts, reduce the affects of yarn streaking and provide patterning effects, a needle bar carrier supports the needle bar, the carrier being secured to the push rod and moving therewith to permit reciprocation of the needle bar, yet permitting the needle bar to slide relatively to the push rod. The transverse or lateral drive for the needle bar generally is supplied by a pattern controlled shifter attachment which supplies the jogging or sliding motion to the needle bar. In the prior art, the apparatus for jogging the needle bar in accordance with the motions provided by the pattern controlled shifter includes a pair of rollers which straddle a plate or block carried by the needle bar and are attached to a drive rod connected to the shifter. As the needle bar reciprocates, the rollers roll up and then down in contact with the plate or block, and yet the block is moved laterally in accordance with the pattern control shifter.
This connection between the shifter drive rod and the needle requires that the rollers reverse rotational direction each time the needle bar reverses direction during its reciprocating cycle. For example, as the needle bar moves downwardly, the rollers first rotate in one direction, and as the needle bar reaches bottom dead center and reverses direction, the rotational direction of the rollers must change. The rollers are hardened cam followers and the plate or block must also be hardened steel to prevent excessive wear. Normally one of the rollers is adjustable relative to the other roller, and as wear occurs the adjustable roller is adjusted to remove play which evolves. In high speed tufting machines, the needle bar reciprocates rapidly and the rotational directions of the rollers reverse quickly. The frictional forces resulting from such rapid reversals of direction therefor increase dramatically with higher speed tufting machines.